Always prepared. Brass golems have brilliant tactical minds, and are always prepared. The brass golem may declare a single action which it took prior to the encounter (even if it didn't know the encounter was going to take place) which helps it in this exact scenario. This must be an action it was capable of.

Master linguist. Brass golems can read, understand, and speak any language, including languages new or previously unknown to them.

Analytics. Studying its target's behaviour, the brass golem notices a pattern to its actions. It grant all allies within 30' a +1d6 bonus to attack the target until the start of its next turn.